The present invention is directed to a device for non-verbal assessment of visual acuity. Numerous arrangements of this general type are shown in the prior art U.S. Pat. Nos. 2,033,529, 2,352,500, 2,385,992, 2,463,813, 3,355,237, 3,477,779, and 3,623,799.
One method of assessing visual acuity, known as Ohm's method, includes a number of separate drums, the surfaces of which consist of alternating black and white stripes of varying widths or dots, figures or similar configurations. Ohm used different drums with different patterns for each testing level. This meant that several drums were necessary.